4.5 [CSS-Level1-2008] Section 5.4.7, text-indent


The [CSS-Level1-2008] specification states:

 Section 16.1:
 Value:                 <length> | <percentage>
 Initial:               0
 Applies to:            block-level elements
 Inherited:             yes
 Percentage values:     refer to parent element's width

Quirks Mode and IE7 Mode (All Versions)

The percentage is evaluated with regards to the width of the containing block rather than the width of the parent element (which may not be a block-level element).